How does a long-distance call work?
Whenever you make a long-distance call, there is an amazing amount of computer technology working to make your call happen. In order to understand the computerized systems used today, however, it is helpful to go back in time and look at how human beings once routed long-distance calls. Think back to a time when a human being worked in a town’s central office. The phone company would build the central office in the middle of town, and then run a pair of copper wires to every home (see How Telephones Work for details on the wiring). The operator — let’s call her Mabel — would work in the central office. Mabel would sit in front of a switchboard, and on this switchboard would be a collection of sockets — one socket for each of the phones in town. When you wanted to place a call: • You would pick up your phone. • A light above your phone’s socket would turn on. • Mabel would plug a jack into your socket and ask you who you would like to talk to. • Mabel woul
